<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <!-- 修复前（错误示例） -->
    <!-- <link rel="stylesheet" th:href="@{/css/styles.css}" href="/css/styles.css"> -->
    
    <!-- 修复后 -->
    <link rel="stylesheet" th:href="@{/css/styles.css}">
    <title>Main Page</title>
</head>
<body>
    ...
</body>
</html>